Cilfrew
Wales · TV
Position 51.672868, -3.772638 Grid reference SS77529861 Nation Wales Ground height 85 m Antenna height 29 m Aerial group Group K — C21–48, wideband across the post-clearance band Polarisation Vertical BBC region Wales ITV region Wales ITV news region Wales Parent transmitter Kilvey Hill Ofcom site number 10616 The position is our conversion of Ofcom's grid reference SS77529861 from OSGB36 to WGS84 [V] . Ofcom publish no latitude and longitude for television sites. The transform is verified rather than assumed: on the 3,403 radio records that carry both, it reproduces Ofcom's own coordinates to within 0.1 m. OpenStreetMap has a mast 8 m away, matched on a name match [V] . That is an independent check on the position, not a correction to it — see how positions were checked .
How far it reaches The share of the UK's 238,895 Census Output Areas where this mast is the strongest signal of its kind. Not the share it reaches at all — most places can receive several transmitters, and only one of them can be the best.
This is a share of areas, deliberately, and not a number of homes. Checked against Ofcom's own published coverage, this model gets the ranking of transmitters right (Spearman 0.861) and over-states how far each one gets by a median factor of 2.5. A share is a ranking statement and survives that; a household count would not, so there isn't one. How this is worked out .
On the map
Where Cilfrew is the strongest signal for television.
Television This site carries the three public-service multiplexes and none of the three commercial ones, which is the normal arrangement at a relay — 1,059 of 1,169 sites are like this. Channels on SDN, ARQ A and ARQ B are simply not transmitted here, and no aerial will recover them; they need a main station. PSB3 (BBC B) is the UK's only DVB-T2 multiplex and carries every HD channel. Losing the HD channels while keeping the rest is therefore a single-multiplex fault rather than an aerial problem.
Transmitter data is Ofcom's; every dataset and the terms it is used under are listed under sources . Coverage figures are modelled, not measured, and are systematically optimistic .